netdev - [PATCH iproute2] utils: bump max args number to 256 for batch files

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Message-ID: <4a0fcf72130d3ef5c4ca91b518f66ac6449cf57f.1622565590.git.gnault@redhat.com>
Date:   Tue, 1 Jun 2021 19:09:31 +0200
From:   Guillaume Nault <gnault@...hat.com>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     netdev@...r.kernel.org
Subject: [PATCH iproute2] utils: bump max args number to 256 for batch files

Large tc filters can have many arguments. For example the following
filter matches the first 7 MPLS LSEs, pops all of them, then updates
the Ethernet header and redirects the resulting packet to eth1.

filter add dev eth0 ingress handle 44 priority 100 \
  protocol mpls_uc flower mpls                     \
    lse depth 1 label 1040076 tc 4 bos 0 ttl 175   \
    lse depth 2 label 89648 tc 2 bos 0 ttl 9       \
    lse depth 3 label 63417 tc 5 bos 0 ttl 185     \
    lse depth 4 label 593135 tc 5 bos 0 ttl 67     \
    lse depth 5 label 857021 tc 0 bos 0 ttl 181    \
    lse depth 6 label 239239 tc 1 bos 0 ttl 254    \
    lse depth 7 label 30 tc 7 bos 1 ttl 237        \
  action mpls pop protocol mpls_uc pipe            \
  action mpls pop protocol mpls_uc pipe            \
  action mpls pop protocol mpls_uc pipe            \
  action mpls pop protocol mpls_uc pipe            \
  action mpls pop protocol mpls_uc pipe            \
  action mpls pop protocol mpls_uc pipe            \
  action mpls pop protocol ipv6 pipe               \
  action vlan pop_eth pipe                         \
  action vlan push_eth                             \
    dst_mac 00:00:5e:00:53:7e                      \
    src_mac 00:00:5e:00:53:03 pipe                 \
  action mirred egress redirect dev eth1

This filter has 149 arguments, so it can't be used with tc -batch
which is limited to a 100.

Let's bump the limit to the next power of 2. That should leave a lot of
room for big batch commands.

Signed-off-by: Guillaume Nault <gnault@...hat.com>
---

Note: I have no production use case for MPLS stacks with 7 LSEs at the
      moment, but 7 is the maximum depth the flow dissector can handle,
      and having the possibility to express such rules with tc -batch
      would help testing the kernel API (writing scripts that generate
      filters, without worrying about the 100 parameters limit).

 lib/utils.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/utils.c b/lib/utils.c
index 93ae0c55..d5496e45 100644
--- a/lib/utils.c
+++ b/lib/utils.c
@@ -1714,10 +1714,10 @@ int do_batch(const char *name, bool force,
 
 	cmdlineno = 0;
 	while (getcmdline(&line, &len, stdin) != -1) {
-		char *largv[100];
+		char *largv[256];
 		int largc;
 
-		largc = makeargs(line, largv, 100);
+		largc = makeargs(line, largv, 256);
 		if (!largc)
 			continue;	/* blank line */
 
-- 
2.21.3